Worst 2013 free-agent signings

Mike Wallace hasn't had a huge impact for Miami this season. Steve Mitchell/USA TODAY

After checking in on the league's best free-agent bargains, it's now time to look at the players who have failed to live up to their open-market expectations. As mentioned last week, the best teams build through the draft while spending wisely in free agency. Nothing can derail a franchise more quickly than a misguided dispersion of resources on players who are unable to produce in line with their lofty price tags -- whether it's because they already have passed their prime, have lost motivation by newfound security or simply are a bad fit in their new situation.

The old adage that free agents are often paid for what they have done rather than what they will do is a scary one, given the often precipitous drop-off seen every year among veteran players, combined with the yearly influx of draftable players with comparable skill sets for just a fraction of the price.

Many will cite the comfortable nature of bidding on a known NFL commodity as an advantage of free agency, but, as we've seen through the years, there are few guarantees in the NFL, and the list below is just a quick sample of the volatile nature of free agency.

Here are the worst free-agent signings of this past offseason so far:

The flashy signing

Mike Wallace, WR, Miami Dolphins (5 years/$60 million)
One of the most heralded offseason signings has gotten off to a rocky start, as Wallace is grading at minus-4.2 from PFF through six games. Before diving into the numbers, the thought of him drawing coverage and opening up the field for other receivers should at least be acknowledged, but I'd venture to guess the Dolphins expected to get more than a $60 million decoy. So, although there is some validity to the point that Wallace is getting extra attention from opposing defenses, the production has to match the contract at some point.